Changing the Brush Size

app/src/main/java/com/dragosholban/androiddrawing/DrawingView.java

@@ -17,6 +17,8 @@
    private ArrayList<Path> paths = new ArrayList<>();
    private ArrayList<Integer> colors = new ArrayList<>();
    private int currentColor = 0xFF000000;
    private ArrayList<Integer> widths = new ArrayList<>();
    private int currentWidth = 6;

    public DrawingView(Context context) {
        super(context);
@@ -38,6 +40,7 @@ public DrawingView(Context context, @Nullable AttributeSet attrs, int defStyleAt
    public void addPath(Path path) {
        paths.add(path);
        colors.add(currentColor);
        widths.add(currentWidth);
    }

    public Path getLastPath() {
@@ -57,7 +60,7 @@ protected void onDraw(Canvas canvas) {
            Paint paint = new Paint();
            paint.setColor(colors.get(i));
            paint.setStyle(Paint.Style.STROKE);
            paint.setStrokeWidth(3f);
            paint.setStrokeWidth(widths.get(i));
            canvas.drawPath(path, paint);
            i++;
        }
@@ -66,4 +69,8 @@ protected void onDraw(Canvas canvas) {
    public void setCurrentColor(int color) {
        currentColor = color;
    }

    public void setCurrentWidth(int width) {
        currentWidth = (width + 1) * 2;
    }
}

app/src/main/java/com/dragosholban/androiddrawing/MainActivity.java

@@ -4,10 +4,12 @@
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.SeekBar;

public class MainActivity extends AppCompatActivity {

    DrawingView drawingView;
    SeekBar seekBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
@@ -16,6 +18,24 @@ protected void onCreate(Bundle savedInstanceState) {

        drawingView = findViewById(R.id.canvas);
        drawingView.setOnTouchListener(new TouchListener());

        seekBar = findViewById(R.id.seekBar);
        seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                drawingView.setCurrentWidth(progress);
            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {

            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {

            }
        });
    }

    public void setColor(View view) {

app/src/main/res/layout/activity_main.xml

@@ -31,7 +31,7 @@
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:orientation="horizontal"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintBottom_toTopOf="@+id/seekBar"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent">
        <View
@@ -63,4 +63,16 @@
            android:background="#000000"
            android:onClick="setColor"/>
    </LinearLayout>
    <SeekBar
        android:id="@+id/seekBar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:max="9"
        android:progress="2"
        app:layout_constraintBottom_toBottomOf="parent" />
</android.support.constraint.ConstraintLayout>